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So lets consider this situation:

I am in inertial system and i have a standing rod with length L_{o}. Then there is a constant force F accelerating this rod. Will the rod's length shorten? Can i use the equation of length-contraction in case velocity is not constant (of course the velocity of the rod can be calculated before)?

Now imagine that i dont have a rod but 2 separate bodies, distance between them is L_{o}. The SAME force applies to both of the bodies. Will the distance (space) between them shorten when they are accelerated? Consider that bodies can be connected with rod so the case is the same described above, is not it?

And the final conclusion. What is the velocity of the shortening? I figured out that the velocity of shortening can be greater than the lightspeed. Note, the velocity of the shortening is dependent on the initial length (distance in case of 2 bodies). So if the L_{o}is enough great, the velocity of the shortening can be arbitrary large even greater than the lightspeed.

(english isnt my first language so if you dont understand something ask and i will enlighten you :D)

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# Accelerating rod's length

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